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A U D I O S I G N A L G E N E R A T O R
1. Using an audio signal generator with a pure
sinusoidal signal, apply a sine wave test signal
at the desired test frequency to the audio
network being tested.
2. Set the signal verator output for the normal
operating level of the circuit being tested.
If desired, the circuit's output may be observed
on the oscilloscope. If the test circuit is over-
driven, the sine wave display on the os-
cilloscope is clipped and the signal level must
be reduced.
3. Connect the CH 1 probe to the output of the
test circuit.
4. Set the S W E E P T I M E / D I V to X - Y .
5. Connect the C H 2 probe to the input of the test
circuit. The input and output test connections
N O A M P L I T U D E
D I S T O R T I O N
N O P H A S E S H I F T
N O A M P L I T U D E
D I S T O R T I O N
P H A S E S H I F T
Fig. 2 5 T y p i c a l phase m e a s u r e m e n t
22
A U D I O
N E T W O R K
B E I N G
T E S T E D
Fig. 2 4 T y p i c a l phase m e a s u r e m e n t alignment set-up
A M P L I T U D E
D I S T O R T I O N
N O P H A S E S H I F T
A M P L I T U D E
D I S T O R T I O N
P H A S E S H I F T
oscilloscope displays
V E R T I C A L
S I Z E
L O A D
to the vertical and horizontal oscilloscope in-
puts may be reversed.)
6. Adjust the CH 1 and C H 2 gain controls for a
suitable viewing size.
7. Some typical results are shown in F i g . 25. If
the two signals are in phase, the oscilloscope
trace is a straight diagonal line. If the vertical
and horizontal gain are properly adjusted, this
line is at a 4 5 ° angle.
produces a circular oscilloscope pattern.
9 0 °
phase shift
cilloscope pattern.
more) than 9 0 ° procedures an elliptical os-
cilloscope pattern. The amount of phase shift
can be calculated from the oscilloscope trace
as shown in F i g . 26.
1 8 0
O U T O F P H A S E
9 0
O U T O F P H A S E
X
- Y
H O R I Z l O N T A L S I Z E
A 9 0 ° phase shift
produces
a circular os-
Phase shift of less (or
S I N E 0=
-f;
W H E R E 0 = P H A S E
A N G L E
Fig. 26 P h a s e shift calculation
A
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